Dead alternator or?

[blizzardwhite]

Hello,
2011 4 Runner 200k Miles on it.
The vehicle has been pretty reliable. Yester I noticed a whine coming from the Engine compartment, which was audible at idle, not so much at speed. I though this was possible a PS pump.

Anyways today, started right up fine, drove for 5 miles, then the dash lights went on: battery, e-brake, abs and TC. When parking it the headlights were very dim. But when it was parked it died. Did not start after that at all. (no clicking starter etc). When parked I noticed a very bad burning electrical smell. Checked under the hood no smoke. Checked an hour later and noticed that the alternator pulley was incredibly hot to the touch.

Battery is an odyssey, and I checked the terminals, they are clean.

So has anyone else had such issues? It seems to me like a bad alternator?

 

[flyrv9]

With the engine off, I would loosen the serpentine belt and remove it from the alternator pulley. Then spin the alternator by hand - it should spin freely with very little force. It should not make any noise or feel like it's grinding. From your description, it sounds like a bad alternator bearing, that may have damaged the alternator. Sometimes they squeal too. You can also smell the alternator to see if anything is burnt. If so, then I'd just replace it. No sense in trying to replace the bearings (if you could locate a rebuild kit) if the field windings have overheated and burnt.

Also, with the belt loose, check all other free spinning and idler pulleys to see that they spin freely.

 

[Humble Leader]

simplest solution is to jump the battery and see if the alternator is charging it. alternator should be putting out ~14v. the dimming headlights is a big clue

the other lights lighting up the dash, also a symptom of failing alternator. as for the burning smell, perhaps you have a valve cover gasket leak that started dripping onto the alternator or somewhere else hot?

 

[blizzardwhite]

Update:
This ended up being a faulty alternator that took out the battery. Replaced them, and now back in service.

 

[Humble Leader]

Update:
This ended up being a faulty alternator that took out the battery. Replaced them, and now back in service.

glad it was sorted. I suppose the good thing here is if I ever see those dash lights come on I better get to a dealer ASAP because bad times are ahead if I don't

did you have the truck towed to a dealer? or did the repair yourself? I always wondered how service depts. get cars that don't run into their shop to fix them. I presume a tow truck just leaves it in the lot?

 

[2021nightshade4x4]

Update:
This ended up being a faulty alternator that took out the battery. Replaced them, and now back in service.

Is it true that a faulty alternator can actually produce an increased voltage and kill a battery that way, in addition to the output decreasing and battery cells failing due to deep discharge?


Sent from my iPhone using Tapatalk

 

[catrains]

well many vehicles had over 200K miles and the alternator has to be replaced . then the battery voltage drops a charge and the battery looses power. I put on my 2016 runner vehicle , display scan gauge I read the voltage/transmission temp/engine temp/gas mileage and other displays .

my 2000 silverado alternator damaged the voltage regulator .. had corrosion on it ..

 

[bigdaddy2021]

Update:
This ended up being a faulty alternator that took out the battery. Replaced them, and now back in service.

That was the only thing that went wrong with my first gen 4runner with a 22RE. Alternator took a dirt nap and ate a battery.

Put in a fresh Alt. and battery and was back up for years w/ just brakes, tires and oil changes.

Fingers-crossed that my 5th gen is the same.